Bake cake according to package directions in a 13x9 inch pan. Allow to cool completely.
With a drinking straw poke even rows of holes across the cake. I did 12 rows of 15.
Dissolve the blue Jello in ¾ cup of boiling water. Fill the holes in every other row with the dissolved blue Jello. You can carefully pour or spoon it in or use a dropper or syringe to be more precise.
Repeat with the red Jello filling the empty rows of holes.
Cover the cake and place it in the fridge overnight or for at least 8-10 hours.
Once the cake has cooled it is time to make the frosting.
This frosting is like a thick and sturdy whipped cream. It is light and creamy like whipped cream but will hold up on a frosted cake in the fridge for a few days.
Like whipped cream it need to be made with cold ingredients and works best if the bowl it is being made in is cold too. You can place the mixing bowl in the freezer for about 15-30 minutes before making the icing.
In the chilled bowl cream together cream cheese, vanilla, and powdered sugar until well mixed and light and fluffy. With the mixer on low/med slowly pour in the whipping cream and mix until well incorporated and smooth.
Turn the mixer to high and whip until stiff peaks form.
Spread evenly across the top of the cake or pipe it on with an icing bag. Sprinkle with red white and blue sprinkles.
Keep covered and refrigerated until ready to serve.